Overload release clutch



Patented Nov. 11, 1947 OVERLOAD RELEASE CLUTCH Walter C. Steinmetz, Columbus, Ohio, assignor,

by mesne assignments, to The Jeffrey Manufacturing Company, a corporation of Ohio Application June 27, 1944, Serial No. 542,409

7 Claims. 1

This invention relates to an overload release mechanism for releasably interconnecting a driving and a driven member.

An object of the invention is to provide overload release mechanism in which a fluid, and preferably a, non-compressible fluid, is trapped in a column and releases in response to a predetermined pressure exerted on a piston connected with said column.

A further object of the invention is to provide such an overload release device in which, upon operation of the releasing mechanism, the fluid will flow into an accumulator or receiver and be stored for subsequent introduction into the system after the parts are re-set to their operative position,

Other objects of the invention will appear hereinafter, the novel features and combinations being set forth in the appended claims.

In the accompanying drawings,

Fig. 1 is an elevational view of a driving sprocket and driven shaft, the latter being shown in section, incorporating the structure of my invention;

Fig. 2 is a sectional view taken on the line 22 of Fig. 1, looking in the direction of the arrows; and

Fig. 3 is a sectional view taken on the line 33 of Fig. 1, looking in the direction of the arrows.

As illustrated in the drawing, the overload release mechanism of my invention is shown interconnecting a driving sprocket and a driven shaft, though it is obvious that a wide variety of driving and driven members may be employed and incorporate said invention.

In said illustrated embodiment there is a driving sprocket IE] having a hub formed of an outer hub ring II which is integral with the rim of sprocket l9, and an inner hub cylinder I2 which is keyed to a, driven shaft I3. The hub ring II may be considered as the driving member, and the hub cylinder I2 aS the driven member. These two hub members I I and I2 are held against axial movement by means of a ring IA, attached to the hub ring II by spaced screws, which provides a circumferential groove with the hub ring I I into which extends a. circumferential projection I5 formed as an integral part of the hub cylinder I2. The hub ring II. is mounted on the hub cylinder I2 so that relative rotation between them is provided except for an overload release mechanism I6 which provides a, normal driving connection between the two.

The overload release mechanism It includes a radial recess or d'etent II formed in the inner surface or bore of the hub ring I I. As illustrated in Fig. 1 of the drawings, this radial recess extends through an arc of approximately 30 or more, but, if desired, it may be much smaller. The radial extent indicated is provided in case exact radial alinement between the hub cylinder I2 and the hub ring I I is not necessary.

The recess or detent Il provides a cam or cam acting surface and it receives a detent I8 which is preferably provided with an anti-friction roller I9 mounted on a pin 26, the detent I8 extending radially beyond the periphery of the hub cylinder I2 and into the radial recess ll of the hub ring I I, with the roller I9 preferably rolling On and contacting with the bearing or camming surface provided by the recess Il, If desired, the roller I9 may be omitted, providing a sliding contact between the detent I8 and the bottom or cam surface of the radial recess l'l.

At least the bottom portion and preferably substantially the entire peripheral portion of the detent I8 provides a piston which fits into a radial cylindrical bore 2| formed in the hub cylinder I2. Said detent or piston I8 is provided with a leather or other desirable type of fluid tight packing 22-, providing a substantially leak-proof sliding relation between the piston I 8 and the interior cylindrical surface of the bore 2!.

The bottom of the cylinder 2| communicates with a passageway 23 formed in the hub cylinder I2 and communicating with a relief valve 24 (see Figs. 1 and 3). The relief valve 24 includes a seat member 25 having a stem 26 surrounded by a helical spring 21 which at one end abuts the seat member 25 and at the other end abuts a removable spring tension adjusting closure nut 28, which closes one end of a recess 29 formed in the hub cylinder I2 within which the operating parts of the relief valve 24 are contained. The seat member 25 normally seats against the periphery of a bore 30 which leads from the passageway 23 to the recess 29. By adjusting the compression of spring 2! the overload will release at adjustable loads.

Under normal conditions the aforedescribed cylindrical bore 2| and the passageway 23 are filled with fluid, preferably a non-compressible fluid, such as oil, grease or even water, though oil is the preferred. fluid of all of them. Thus a trapped fluid column is providedv that fills completely the cylinder 2| below the packing 22 and completely fills the passageway 23. This holds the detent IB into-the recess I1 and thus provides a driving connection between the driving member and the driven member l2 or between the driving sprocket l and the driven shaft l3.

Upon the occurrence of a predetermined overload, camming'action between the cam surface provided by the recess l1 and the detent l3, will cause sufiicient pressure to be developed in the hydraulic fluid in the cylinder 2| and passageway 23 to open the high pressure relief valve 24 and allow a sufiicient amount of the hydraulic fluid or oil to flow through the passageway 23 and past the seating members 25 and 30 of the relief valve 24 and flow into the recess 29 from which it will flow along a path hereinafter described.

This release of the trapped column of fluid under predetermined pressure, of course, will permit the detent or piston l8 to travel radially inwardly sufficiently to allow the driving member or ring H to rotate about the driven member or cylinder l2, thus providing for a releasing driving connection between said driving and driven members.

In the preferred embodiment of my invention apparatus is provided to prevent the loss of the hydraulic fluid, such as oil or grease. To this end,

such hydraulic fluid as is delivered to the recess 29, will flow therefrom by means of a passageway 3| in the hub cylinder l2 and be delivered to the cylindrical bore 32 of an accumulator or receiver 33, said bore 32 being formed in the hub cylinder l2.

The accumulator or receiver 33 includes a spring-pressed piston 34 provided with a seal 35 and a spring 36 working against the piston 34 and a removable head 31.

It is evident that hydraulic fluid delivered to the passageway 3| under pressure, as it passes through the overload relief valve 24, will flow against the piston 34 and move it to the left as viewed in Fig. 2 of the drawings, compressing the spring 36. In other words, the hydraulic fluid which is pushed from the cylinder 2| in response to an overload release, will be accumw lated in the accumulator 33 for future use.

Communicating with the passageway 3| is a check valve operating fitting 38 by which new hydraulic fluid, oil or grease, may be introduced thereinto to compensate for any loss thereof. This fitting will also be employed when the ap paratus is initially filled with the fluid.

To restore the detent |8 to a driving position and thus to interlock the driving and driven members therethrough, following a release thereof, mechanism is provided to deliver the fluid from the accumulator 33 back to the cylinder 2| to move the piston or detent l8 radially outwardly. Such mechanism includes a passageway 39 formed in the hub cylinder l2 and communicating from the bore 32 to the right of the piston 34, as viewed in Fig. 2 of the drawing, and leading to a manually operable needle valve 43 which controls the flow of said hydraulic fluid from the passageway 39 to a passageway 4| by way of a bore 42. The passageway 4| communicates directly with the cylinder or bore 2| inwardly of the piston to and packing 22. Obviously, by unseating the needle valve 49, the accumulator 33 will act under the influence of its spring 36 to force the hydraulic fluid accumulated therein through the passageways 39 and 4| by way of bore 42 to push the piston or detent l8 radially outward, as permitted by the re-alined condition of the hub ring l and the hub cylinder l2. Thus the hydraulic fluid will again be trapped in the cylinder 2| and radially inwardly of the piston l8 after the nee valve 40 is closed.

In the operation of the device the various parts will be in the positions illustrated in the drawing, and the detent l8 will be received in the recess I? to provide a releasable driving connection between the driving member H), H and the driven member l2, l3. The bore 2| below packing 22, and passageways 23, 3|, 39 and 4| will be filled with oil, grease or liquid preferably devoid of compressible fluid or air. Upon the occurrence of an overload condition on the driven member, the camming action between the bearing surface of the ring H adjacent the radial recess I1 and the detent H3, or more specifically the roller l9 thereof, will force the piston or detent I8 radially inwardly, with sufficient pressure being created in the hydraulic fluid, gas, oil or grease, to open the high pressure relief valve 24, thus permitting escape of the trapped column of fluid and permitting it to flow through passageways 23 and 3| by way of recess 29 into the accumulator 33 where it may be stored for future use.

After the overload condition has been removed, or, if desired, a test to see if it has cleared, the operator will open the needle valve 32 following alinement of the detent i8 with the recess H, and the spring 38 of the accumulator 33 will force the hydraulic fluid through the passageways 39 and 4| by way of bore 42 to move the detent l8 radially outwardly to re-seat the desired releasable driving connection between the ring I: and cylinder l2. Thereupon, the needle valve 40 will be closed to prevent a reverse flow of the hydraulic fluid back into the accumulator 33 under operating conditions. Thus the parts will be restored to their normal operating positions.

The operation of the device is the same, regardless of the direction of rotation of sprocket 53. That is, it operates equally well in reverse directions of rotation of the driving and driven members. It will be seen that the mechanism is completely reversible in that the shaft may drive the sprocket or the sprocket may drive the shaft and that the device is equally responsive to overload conditions regardless of which member is the driven member.

Obviously those skilled in the art may make various changes in the details and arrangement of parts without departing from the spirit and scope of the invention as defined by the claims hereto appended, and I therefore wish not to be restricted to the precise construction herein disclosed.

Having thus described and shown an embodiment of my invention, what I desire to secure by Letters Patent of the United States is:

1. An overload release device including a driving member and a driven member, means mounting said members for relative rotation, means releasably connecting said members together including a detent, a cylinder, a piston in said cylinder connected to hold said detent normally to provide a driving connection between said members, a relief valve connected with said cylinder, a lubricating fluid in said cylinder normally filling it and operable in response to movement of said piston under the influence of excessive load on said detent to force said fluid through said relief valve, an accumulator connected to receive fluid passing through said relief valve and storing it under pressure, and valve means operable to deliver the fluid from said accumulator back to said cylinder when said piston is restored to its normal position.

2. An overload release device including a driving member and a driven member, means mounting said members for relative rotation, means releasably connecting said members together including a detent, a cylinder, 'a piston in said cylinder connected to hold said detent normally to provide a driving connection between said members, a relief valve connected with said cylinder, a fluid in said cylinder normally filling it and operable in response to movement of said piston under the influence of excessive load on said detent to force said fluid through said relief valve, an accumulator connected to receive fluid passing through said relief valve and storing it under pressure, and means operable to deliver the fluid from said accumulator back to said cylinder when said piston is restored to its normal position.

3. A manually resettable overload release mechanism adapted to sever completely its driving function in response to an overload driving condition untilreset including a driving member and a driven member bearinged for rotation with respect to one another on a common axis, one of said members including a cylinder positioned to one side of said axis and a fluid receiving chamber and the other of said members including means forming a detent, a piston in said cylinder having detent means engaging said first named detent tending to hold said driving and driven members to rotate together and being depressed whenever they rotate relative to each other because of overload on the driven member, a substantially noncompressible fluid trapped in said cylinder and acting against said piston to extend said piston detent means to engage said first named detent means, a relief valve connected with said cylinder operable only in response to a predetermined fluid pressure in said cylinder for exhausting fluid therefrom into said fluid receiver, and manually operable valve means through which fluid may be introduced into said cylinder to reset said overload release mechanism.

4. A manually resettable reversible overload release mechanism adapted when operated to sever completely its driving function including a driving member and a driven member, one of said members including a hub having a radially extending cylinder and a fluid receiver formed therein, the other of said members fitting and bearinged for rotation upon said hub and having a recess formed therein, a piston in said cylinder having detent means extending into said recess in said other member tending to hold said driving and driven members to rotate together and being depressed whenever they rotate relative to each other because of overload on the driven member, a substantially non-compressible fluid trapped in said cylinder and acting against said piston to extend said piston detent means into said recess, a relief valve connected with said cylinder operable in response to a predetermined fluid pressure in said cylinder for exhausting fluid therefrom into said fluid receiver, and manually operable valve means through which fluid may be introduced into said cylinder to reset said overload release mechanism.

5. A resettable reversible overload release mechanism adapted when operated to sever completely it driving function including a driving member and a driven member, one of said members including a hub having a radially extending cylinder formed therein, the other of said members fitting and bearinged for rotation upon said hub and having a recess formed therein, a piston in said cylinder having detent means extending into said recess in said other member tending to hold said driving and driven members to rotate together and being depressed whenever they rotate relative to each other because of overload on the driven member, a substantially non-compressible fluid trapped in said cylinder and acting against said piston to extend said piston detent means into said recess, a relief valve connected with said cylinder operable in response to a predetermined fluid pressure in said cylinder for exhausting fluid therefrom, and valve means through which fluid may be introduced into said cylinder to reset said overload release mechanism.

6. A resettable reversible overload release mechanism adapted when operated to sever completely its driving function including a driving member and a driven member, one of said members including a hub having a cylinder formed therein positioned to one side of the axis thereof, the other of said members fitting and bearinged for rotation upon said hub and having a recess formed therein, a piston in said cylinder having detent means extending into said recess in said other member tending to hold said driving and driven members to rotate together and being depressed whenever they rotate relative to each other because of overload on the driven member, a substantially non-compressible fluid trapped in said cylinder and acting against said piston to extend said piston detent means into said recess, a relief valve connected with said cylinder operable in response to a predetermined fluid pres-' sur in said cylinder for exhausting fluid therefrom, and valve means through which fluid may be introduced into said cylinder to reset said overload release mechanism.

7. A reversible overload release mechanism adapted when operated to sever completely its driving function including a driving member and a driven member, one of said members including a hub having a cylinder formed therein positioned to one side of the axis thereof, the other of said members fitting and bearinged for rotation upon said hub and having a recess formed therein, a piston in said cylinder having detent means extending into said recess in said other member tending to hold said driving and driven members to rotate together and being depressed whenever they rotate relative to each other because of overload on the driven member, a substantially non-compressible fluid trapped in said cylinder and acting against said piston to extend said piston detent means into said recess, and a relief valve connected with said cylinder operable in response to a predetermined fluid pressure in said cylinder for exhausting fluid therefrom.

WALTER. C. STEINMETZ.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,919,437 LeFevre July 25, 1933 2,293,786 Worden Aug. 25, 1942 FOREIGN PATENTS Number Country Date 544,230 Great Britain Apr. 2, 1942 611,897 Germany 1935 

